Surface modifying macromolecules for biomaterials.

Abstract

In this thesis, new biomaterials were developed by incorporating surface modifying macromolecules (SMMs) that enriched the surface with a fluoro-chemistry. The SMMs contained a linear polyurethane as the prepolymer component and the prepolymer was end-capped by a fluorinated alcohol. The SMM materials and the blend of these SMMs with the polyester-urea-urethane base polymer were characterized with respect to their bulk and the surface properties, response to their biodegradation in the presence of enzyme and their fibrinogen adsorption characteristics. The SMMs were found to have selectively migrated to the surface of the polymer mixtures as expected. The bulk thermal (e.g. glass transition temperature) were found to be unaltered for polyurethane samples containing up to 5% SMM. The "fluorine tail" of the SMMs allowed the substrate surfaces to achieve very low surface wettability. Contact angle values (water/air) for the new materials were as high as $116\sp\circ,$ which is higher than that of $\rm Teflon\sp{R}.$ Measurements of fibrinogen adsorption, an indication of the tendency of surfaces to stimulate thrombosis, showed that the SMM blended materials significantly reduced fibrinogen adsorption. A biodegradation test of a polyether-urea-urethane containing one of the SMMs optimized for the polyester-urea-urethane showed that the SMM was unable to inhibit degradation of the polyether-urea-urethane. This suggested that the SMM was not universally effective and that the microstructure of, and the interaction between, SMMs and the base polymer were also important factors to be considered during the investigations of the stability of polyurethanes. (Abstract shortened by UMI.)